1. Field of the Invention
The present invention is directed to an expert system tester that allows extensive expert system rulebased testing without the test program having any knowledge of the particular rulebase being tested and, more particularly, provides a practical regression testing method for analyzing rulebase changes after a modification has been made which is cost effective and significantly raises rulebase quality.
2. Description of the Related Art
It is common for expert system rulebases to typically exceed a thousand rules and in such systems sensor inputs commonly number in the hundreds. If the sensors are digital sensors providing one of two input values, the number of possible combinations of input values is enormous and testing all combinations is practically impossible. When analog sensors are involved, which have an infinite number of possible input values, the testing problem becomes even greater. During normal development of new rules for a large rulebase, normal debug type of production rule testing by the knowledge engineer is performed. In such a situation when the knowledge engineer produces a new rule, the engineer exercises the system using simulated plant data having values over the expected range of sensor values for the sensors examined by the new rule to verify that the new rule is operating as expected, that is, producing the diagnosis expected when expected. In such a situation, sensor values other than the sensor values used by the new rule are kept at normal values. As a result, production type testing does not determine the effect of other sensors on the new rule or the interaction of the new rule with the remaining rules. A second type of testing is to place the expert system online with real, continuous plant data and have the knowledge engineer carefully examine the diagnoses made to determine whether the diagnoses were intended. It has become apparent that more effective techniques and tools are needed for operational verification of large rulebase and input number systems.